This invention relates generally to an apparatus for severing thin tubing members or casings such as are used to contain prepared meats in the manufacture of sausages and other products. More specifically, the invention relates to an apparatus for severing shirred from unshirred portions of a casing.
Previously, sausage and other similar meat products were made by injecting certain prepared meats into lengths of the intestines of various animals. More recently, artificial cellulosic materials have been substituted for the natural intestine casing. Such artificial casings may be produced in virtually endless lengths. Extremely long lengths, however, may be difficult to handle in the manufacturing of sausage and other similar products. Thus, the thin, artificial casing material is compressed into relatively short axial lengths by shirring, i.e., laying the casing into tight axial folds or overlays. The casing material may thereby be reduced to convenient lengths called "sticks." The shirred sticks may be subsequently injected with prepared meat under sufficient pressure to unshir the stick and fill the previously shirred casing.
Though various methods are employed in the processing of casing into shirred lengths as described above, a conventional method involves the use of a storage roll from which casing material is drawn over a feeding roller and between driving belts. The driving belts grip the casing against the resistance of air pressure introduced into the interior of the casing by an apertured, inflating mandrel around and along which the casing moves. The driving belts direct the casing into a plurality of shirring rollers which shirr or lay the casing in tight folds or overlays to provide a highly compacted, shirred length of material.
Since it is desired commercially that the shirred casing material be cleanly cut, a cutter must be provided. It is in this regard that the present invention is useful in cleanly and quickly severing the shirred casing from the unshirred portion. With regard to this and other applications, the devices of the prior art entail a number of problems, such as those discussed below, which have not been dealt with or which have not been dealt with effectively.
Many of the devices for cutting casings which appear in the prior art may fail to cleanly cut the casing. An ineffective cut may produce loose flags, strands, or tatters in the area in which the casing materials are cut. Such loose flags, strands, or tatters may become embedded in the prepared meats which fill the casings and may be unpleasant to persons consuming the finished product. Such loose flags also may interfere with the forming of a finished sausage into lengths and may hamper the formation of an adequate seal at the end of the sausage.
Of independent significance, the loose flags, strands, or tatters which may result from ineffective cutting of the casing may also hamper satisfactory securement of the prepared casing to the machine which fills the casing with prepared meats. Moreover, these loose flags, strands, or tatters may render the casing more vulnerable to splitting or tearing in the area adjacent thereto.
Those devices of the prior art may be subject to other problems, as well as those of loose flags, strands, or tatters, which may occur at the severed section. These devices may be subject to a further difficulty of residual stresses and distortions introduced into the end of the casing adjacent the point at which the casing was severed by tearing or other such severing operations. Such residual stresses and distortions may render the end of the casing more susceptible to tearing and rupture and may impart irregular shape to the casing. A rupture, of course, may be wasteful of meat and casing. It would thus be desirable if an apparatus could be provided for cutting casings for prepared meats which would avoid residual stresses and distortions in the casings.
Other devices of the prior art which are employed to cut casings for meat may introduce stresses of unacceptable magnitude into the mandrel around and along which the casing is passed. A mandrel which is employed to support and inflate the casing may be rather long and slender and may be supported at only one end. Being loaded with a length of casing, a mandrel of the type just described may be particularly vulnerable to overstressing, fatigue, and fracture, particularly if forces applied to the mandrel are not balanced, or if they are cyclical in application. Fracture of a mandrel as a result of overstressing or fatigue may result in leakage of the inflating medium and may require costly repair during which the machine for preparing the casings may be idle. It would thus be desirable if an apparatus could be provided for cutting the casing for meat which would apply only balanced forces to the mandrel or which would apply no forces whatever to the mandrel.
The shirring of the casing may be conducted at high speeds. In this regard, many of the devices for cutting cashings which appear in the prior art may not function at a sufficiently high speed to provide economical production of the shirred casing materials. These devices may involve a relatively large number of parts which interact in a relatively complicated sequence of operation. Such arrangements may not only slow production but also may be vulnerable to wear and mechanical failure. In addition, such arrangements may require frequent lubrication which may contaminate the casing. Thus, it would be desirable if an apparatus for cutting casings for meats could be provided which could operate at a higher and more economical speed compatible with that of the shirring operation and yet remain simple in construction and relatively maintenance free.
Moreover, devices of the prior art subject to one or more of the problems discussed above may introduce unnecessary costs to the preparation of shirred casing. To the extent loose flags, strands, or tatters product a less acceptable finished product or hamper proper injection of meat into the casing, the cost of the finished sausage or other product may be increased. Similarly, shirred casing unnecessarily weakened may waste both casing and meat and may thus increase costs. Also, a mandrel which fails due to overstressing or fatigue, and which must be replaced also may increase costs of preparing shirred casings as may slow, uneconomical production and the maintenance requirements associated with a complex structure.
A U.S. Pat. No. 3,112,517, issued to Clifford E. Ives is illustrative of certain of the problems discussed above. This patent discloses a device for cutting casing wherein a digger or catch finger lifts and radially engages and penetrates the folds of the shirred casing. Opposed pinch rollers next advance in the direction in which the casing is shirred to unshirr a portion of the casing. Once the pinch rollers pass the catch finger and unshirr a length of casing, a scoring yoke or cutter moves radially to score and tightly clamp the casing against the support mandrel at points of contact on opposite sides of the mandrel. The continued movement of the pinch rollers tears the casing into opposed lengths, leaving triangular flaps, which are referred to as fishtails. The pinch rollers complete the operation by reshirring the unshirred casing.
A particular problem which would seem to occur with the Ives device is that the manner in which the casing is severed may cause undesirable loose flags, strands, or tatters and the associated problems mentioned earlier. It will be recalled from the preceding that the casing is scored and clamped against the mandrel on opposite sides thereof. The casing is subsequently torn into opposed lengths. It would seem apparent that this clamping and tearing may leave undesirable loose flags, strands, or tatters at the point at which the casing is severed.
Furthermore, it appears that the method of cutting casings disclosed by the Ives patent may apply considerable unbalanced force to the long, slender mandrel and thus, may overstress or fatigue the mandrel. It will be noted that considerable unbalanced force may be exerted on the mandrel by the catch finger during penetration between the folds of the shirred casing. Similarly, considerable unbalanced force may be exerted on the mandrel by the scoring yoke which must engage and clamp the casing against the mandrel with sufficient force to score and tightly secure the unshirred casing. It would thus appear that the individual or combined effects of these forces may overstress, fatigue, and eventually fracture the long, slender mandrel.
Finally, it would appear that the Ives device may entail a relatively large number of components which interact in a relatively complex manner. The number of parts would appear to introduce related problems of increased maintenance and lubrication requirements.
A U.S. Pat. No. 3,110,058, issued to Walter V. Marbach discloses a device which may involve many of the problems discussed earlier. The device disclosed in the Marbach patent provides a rotating gripping member on which are disposed pivoting jaws which grip and clamp an unshirred portion of the casing against the mandrel. When the gripping member has been rotated into position and the casing clamped against the mandrel, movement of the gripping member parallel to the longitudinal axis of the mandrel severs the casing at the leading edge of the gripping member by simple overstressing against the resistance of the shirring wheels.
Not only may this device be subject to the problem of loose flags, strands, or tatters which may develop incident to incomplete circumferential gripping of the casing, but also residual stresses and distrotions may be introduced in the portion of the casings adjacent the severed section. Such residual stresses and distortions may cause undesirable weakness and irregularity in shape in the end of the casing as mentioned earlier. Severing the casing by simple overstressing may also not effect the separation at the desired section of the casing. In other words, since an overstressed casing will break at the weakest point along the overstressed length, simple overstressing of the casing may not sever the casing at the desired point.